IPCC Climate Change Data: CSIRO A1a Model: 2050 Minimum Temperature

The CSIRO Atmospheric Research Mark 2b climate model (Hirst et al., 1996, 1999) has recently been used for a number of more sophisticated climate change simulations. These start from 1880 to avoid the "cold start problem". This version of the CSIRO model includes the Gent-McWilliams mixing scheme in the ocean and shows greatly reduced climate drift relative to earlier versions (e.g. Dix and Hunt, 1998). The drift in global mean surface temperature in the new control run is about -0.02 degrees C/century. Note that the model uses flux correction. The model atmosphere has 9 levels in the vertical and horizontal resolution of spectral R21 (approximately 5.6 by 3.2 degrees). The ocean model has the same horizontal resolution with 21 levels. The equilibrium sensitivity to doubled CO2 of a mixed layer ocean version of the model is 4.3 degrees. This is at the high end of the range of model sensitivities (e.g. IPCC 1995, Table 6.3). In the basic greenhouse gas experiment the model combines the effect of all radiatively active trace gases into an "equivalent" CO2 concentration. Observed concentrations are used from 1880 to 1990 and the IS92a projections into the future. This gives close to a 1%/year compounding increase of equivalent CO2. Another model experiment includes the negative radiative forcing from atmospheric sulphate aerosol. The direct aerosol forcing is included via a perturbation of the surface albedo, similarly to the Hadley Centre experiments described by Mitchell et al (1995) and Mitchell and Johns (1997) . The sulphate concentrations are the same as used in the Hadley Centre experiments. However the chosen aerosol optical properties are different, giving a present day forcing due to anthropogenic sulphate of about -0.4 W/m^2. This can be compared to the 1880-1990 greenhouse gas forcing of about 2 W/m^2. The magnitude of the 20th century warming in the model including aerosol matches the observed reasonably well. However there are a number of forcings missing from the model, including solar variability, sulphate indirect effect and the effect of soot. The climate sensitivity of CSIRO-Mk2 is about 4.3 degrees C (Watterson et al.,1997). From the IPCC website: The A1 Family storyline is a case of rapid and successful economic development, in which regional averages of income per capita converge - current distinctions between poor and rich countries eventually dissolve. In this scenario family, demographic and economic trends are closely linked, as affluence is correlated with long life and small families (low mortality and low fertility). Global population grows to some nine billion by 2050 and declines to about seven billion by 2100. Average age increases, with the needs of retired people met mainly through their accumulated savings in private pension systems. The global economy expands at an average annual rate of about three percent to 2100. This is approximately the same as average global growth since 1850, although the conditions that lead to a global economic in productivity and per capita incomes are unparalleled in history. Income per capita reaches about US$21,000 by 2050. While the high average level of income per capita contributes to a great improvement in the overall health and social conditions of the majority of people, this world is not without its problems. In particular, many communities could face some of the problems of social exclusion encountered by the wealthiest countries in the 20th century and in many places income growth could come with increased pressure on the global commons. Energy and mineral resources are abundant in this scenario family because of rapid technical progress, which both reduce the resources need to produce a given level of output and increases the economically recoverable reserves. Final energy intensity (energy use per unit of GDP) decreases at an average annual rate of 1.3 percent. With the rapid increase in income, dietary patterns shift initially significantly towards increased consumption of meat and dairy products, but may decrease subsequently with increasing emphasis on health of an aging society. High incomes also translate into high car ownership, sprawling suburbanization and dense transport networks, nationally and internationally. Land prices increase faster than income per capita. These factors along with high wages result in a considerable intensification of agriculture. Three scenario groups are considered in A1 scenario family reflecting the uncertainty in development of energy sources and conversion technologies in this rapidly changing world. Near-term investment decisions may introduce long-term irreversibilities into the market, with lock-in to one technological configuration or another. The A1B scenario group is based on a balanced mix of energy sources and has an intermediate level of CO2 emissions, but depending on the energy sources developed, emissions in the variants cover a very wide range. In the fossil-fuel intensive scenario group A1FI, emissions approach those of the A2 scenarios; conversely in scenario group A1T with low labor productivity or of rapid progress in "post-fossil" energy technologies, emissions are intermediate between those of B1 and B2. These scenario variants have been introduced into the A1 storyline because of its "high growth with high tech" nature, where differences in alternative technology developments translate into large differences in future GHG emission levels Ecological resilience is assumed to be high in this storyline. Environmental amenities are viewed in a utilitarian way, based on their influence on the formal economy. The concept of environmental quality might change in thisstoryline from"conservation" of nature to active "management" - and marketing - of natural and environmental services. Data are available for the following periods: 1961-1990, 2010-2039; 2040-2069; and 2090-2099 Mean monthly and change fields.澳大利亚联邦科学与工业研究组织（CSIRO）大气研究部Mark 2b型气候模型（Hirst等，1996、1999）近期已被用于多项更复杂的气候变化模拟试验。该类试验始于1880年，以规避"冷启动问题（cold start problem）"。此版本的CSIRO模型在海洋模块中引入了Gent-McWilliams混合方案，相较于早期版本（如Dix与Hunt，1998），其气候漂移现象已大幅缓解。新控制试验中，全球平均地表温度的漂移速率约为-0.02℃/世纪。需注意，该模型采用了"通量校正（flux correction）"方案。其大气模块垂直方向共设9层，水平分辨率采用谱模式R21（spectral R21）（约5.6×3.2个纬度/经度度）；海洋模块水平分辨率与大气模块一致，垂直方向设21层。该模型混合层海洋版本的二氧化碳加倍平衡气候敏感度为4.3℃，处于各类模型敏感度区间的上限（如政府间气候变化专门委员会（IPCC），1995，表6.3）。 在基础温室气体试验中，模型将所有辐射活性痕量气体（radiatively active trace gases）的影响整合为"等效二氧化碳浓度（equivalent CO₂ concentration）"。1880-1990年采用观测浓度，未来时段则采用IS92a情景预估（IS92a projections），这使得等效二氧化碳浓度以约1%/年的复合速率增长。另一项模型试验纳入了大气硫酸盐气溶胶产生的负辐射强迫（negative radiative forcing）：其直接气溶胶强迫通过地表反照率（surface albedo）扰动实现，与Mitchell等（1995）及Mitchell与Johns（1997）描述的哈德利中心（Hadley Centre）试验方法类似。硫酸盐浓度与哈德利中心试验所用数值一致，但所选气溶胶光学特性（aerosol optical properties）存在差异，由此得到的当代人为硫酸盐辐射强迫（anthropogenic sulphate radiative forcing）约为-0.4 W/m²，可与1880-1990年约2 W/m²的温室气体强迫（greenhouse gas forcing）进行对比。纳入气溶胶强迫的模型所模拟的20世纪变暖幅度与观测结果较为吻合。不过，模型仍缺失若干强迫因子，包括太阳活动变化（solar variability）、硫酸盐间接效应（sulphate indirect effect）以及黑碳（soot）的影响。CSIRO-Mk2模型的气候敏感度约为4.3℃（Watterson等，1997）。 引自政府间气候变化专门委员会（IPCC）官网的内容如下： A1情景族（A1 Family storyline）的叙事框架为快速且成功的经济发展模式，其中区域人均收入趋于趋同——当前贫富国家之间的界限最终将消失。在该情景族中，人口与经济趋势紧密关联，因为富裕程度与长寿命、小家庭（低死亡率与低生育率）相关联。全球人口到2050年将增长至约90亿，到2100年回落至约70亿。人口平均年龄上升，退休人员的养老需求主要通过其在私人养老金体系中的累积储蓄得到满足。 全球经济到2100年将以年均约3%的速度扩张，这与1850年以来的全球平均增长水平大致相当，尽管推动全球生产率与人均收入提升的条件在历史上前所未有。到2050年，人均收入将达到约21000美元。尽管较高的人均收入平均水平可大幅改善绝大多数人口的整体健康与社会状况，但该情景下的世界仍存在诸多问题。具体而言，诸多社区可能会面临20世纪发达国家曾遭遇的社会排斥问题，且在许多地区，收入增长的同时也会给全球公共资源带来更大压力。 该情景族下能源与矿产资源储量充裕，这得益于快速的技术进步——技术进步既可降低单位产出的资源消耗，又可提升具有经济开采价值的储量。最终能源强度（final energy intensity，即单位GDP能耗）将以年均1.3%的速率下降。随着收入快速增长，饮食结构最初会显著转向更多肉类与乳制品的消费，但随着老龄化社会对健康关注度的提升，后续这类消费可能会有所回落。高收入也会带来私家车保有量的提升、全国乃至全球范围内的郊区蔓延式扩张与密集的交通网络。土地价格的上涨速度快于人均收入。上述因素与高薪资共同推动了农业的大幅集约化发展。 A1情景族下设三个情景组，以反映这个快速变化的世界中能源与能源转化技术发展路径的不确定性。短期投资决策可能会给市场带来长期不可逆性，即市场会锁定于某一种或另一种技术路径。A1B情景组以能源来源的均衡组合为基础，二氧化碳排放水平处于中等区间；但根据所采用的能源技术路径不同，各子情景的排放量差异极大。在化石燃料密集型情景组A1FI中，排放量接近A2情景；与之相反，在劳动力生产率较低或"后化石"能源技术快速发展的A1T情景组中，排放量处于B1与B2情景之间。 鉴于A1情景族具有"高增长、高技术"的特性，不同技术发展路径会导致未来温室气体（GHG）排放量产生巨大差异，因此设置了诸多情景子项。该情景下，生态系统韧性（ecological resilience）被设定为较高水平。环境福祉将以实用主义视角进行评估，即基于其对正规经济的影响。在该情景中，环境质量的概念可能会从"保护自然"转变为对自然与环境服务的主动"管理"乃至"市场化运营"。 本数据集包含以下时段的数据：1961-1990年、2010-2039年、2040-2069年以及2090-2099年的逐月平均与变化场数据。